A Duplighost is presumably a ghost or a creature with a sheet over its body. They look very similar to that of a Lantern Ghost. Their initial attack is by flying into Mario. They also have a trick of their own by transforming themselves into one of Mario's Partners. In Paper Mario, the first one is seen on Shiver Mountain after it duplicates Kooper and tries to fool Mario. Several of them are found inside the Crystal Palace copying Kooper once again and Bombette. At one point when a few duplighosts try to shift into Kooper, their disguises fail and end up tranforming themselves into Goompa, Kolorado, Koopa Koot, and even Luigi. Later in Bowser's Castle, a Duplighost takes the form of Peach, trying to trick Mario and his partners that she "Managed to escape from Bowser" and that Mario no longer needs to worry. Though, Goombario already seems to be suspicious of this action when tattling on her. In Paper Mario: The Thousand Year Door, a Duplighost named Doopliss is able to steal or take the form of Mario's body, a power that's not seen previously within a Duplighost. When Doopliss takes the form of Mario, he fools Mario's partners, so in the battle, you must fight your partners as well as Doopliss. The only "good" duplighost in the series so far is Lee, a fighter at Toad Town's Dojo.

"It's a Duplighost disguised as me. It'll do Headbonk and Tattle. That looks nothing like me. Does it? No! Seriously though, does it? Mario? Hello? Look, I've been working out like crazy trying to get in shape for adventuring. There's just no way I'm that pudgy!"

"It's a Duplighost disguised as Kooper. This impostor almost looks better than the original! Ha! Its disguise is pretty much perfect. Its attack power is exactly the same as the character it's imitating. It's probably not very difficult for this Duplighost to disguise itself as Kooper. After all, our pal is pretty unusual looking. It'll attack us with its shell, just like the regular Kooper. You'll have the best luck beating it if you flip it."

"It's a Duplighost disguised as Parakarry. He looks even more intelligent as an enemy. Its disguise is pretty much perfect. Its attack power is exactly the same as Parakarry's. Don't underestimate him, Mario. He looks pretty serious."

"It's a Duplighost disguised as Bow. Its disguise is pretty much perfect. Its attack power is exactly the same as Bow's. Look, you've seen her in action. Do you really want to know what a Smack Attack feels like?"

"It's a Duplighost disguised as Watt. Its disguise is pretty much perfect. Its attack power is exactly the same as the character it's imitating. You know how Watt is shocking? Same goes for this Duplighost."

"It's a Duplighost disguised as Sushie. Its face looks even grouchier than the real thing! Its disguise is pretty much perfect. Its attack power is exactly the same as Sushie's. I'm glad we have Sushie on our side. She's intimidating! I wonder if this impostor is meddlesome as well..."

"It's a Duplighost disguised as Lakilester. It's hard to take him seriously. Its disguise is pretty much perfect. Its attack power is exactly the same as Lakilester's. It's tough to dodge his Spiny Flip, so pay attention."